It’s bad enough for General Mills that Americans have been losing interest in breakfast cereal for the past decade or more, but the brand got more bad news last week when the Trademark Trial and Appeal Board rejected its application to trademark the use of yellow on Cheerios boxes.

The problem for the packaged-foods giant wasn’t so much that consumers didn’t recognize Cheerios’ famous yellow box; it was that too many other cereals were already using yellow on their boxes. Shoppers who are “accustomed to seeing numerous brands from different sources offered in yellow packaging are unlikely to be conditioned to perceive yellow packaging as an indicator of a unique source,” wrote Judge Anthony R. Masiello in his decision. “Rather, they are more likely to view yellow packaging simply as eye-catching ornamentation customarily used for the packaging of breakfast cereals generally.”